Control Global

Greg McMillan and Stan Weiner Speak with Electrochemical Measurements Expert Jim Gray About the pH Electrode and Its Full Potential as a Measuring Tool

Stan: A measurement is only as good as its calibration. The pH electrode has by far the greatest sensitivity and rangeability of any measurement in the process industry. The electrode can function well in a wide spectrum of process fluids and…

This State of Technology Report is a compendium of the latest trends articles, back-to-basics tutorials, application stories and product solutions recently published in the pages of Control—compiled by the editors and all together here in one convenient eBook.

Despite ongoing advances in instrumentation technology, specifying a flowmeter or level gauge that will reliably perform over the anticipated range of process conditions often remains a complex and subtle engineering task.
Dozens of niche…

Process plants and related facilities such as tank farms are filled with vessels, tanks and similar storage units, and most of these units could benefit from a system to measure, monitor and view inventory on a near real-time basis. "Logistical…

Additional information and wireless connectivity are further improving productivity, reliability and efficiency.

Like other facilities that have been using the HART Communication Protocol for any amount of time, previous recipients of the HART Plant of the Year Award have been busy reaping even more of the benefits the technology provides. These benefits…

BLH Nobel Introduced a System That Quickly and Easily Checks Weighing Systems for Wiring and Mechanical Faults

Load cell weighing systems solve some of the knottiest problems in batch and level control by directly measuring masses of solids and liquids as they're accumulated, dispensed or conveyed. But the load cells must be installed and wired properly, and the load structure must be engineered and constructed correctly to distribute the measured load as axial forces on the cells. What appear on the surface to be simple wiring and construction tasks have caused more than a few problems during commissioning and maintenance due to miswired or poorly made connections, distorted or binding structures, incorrectly installed load cells or rigid connections to adjacent equipment.
Such problems often are not found until a new installation is being…

Recent

Greg McMillan and Stan Weiner Speak with Electrochemical Measurements Expert Jim Gray About the pH Electrode and Its Full Potential as a Measuring Tool

Stan: A measurement is only as good as its calibration. The pH electrode has by far the greatest sensitivity and rangeability of any measurement in the process industry. The electrode can function well in a wide spectrum of process fluids and…

This month, the editors of Control browse the web to get you the latest online resources on loop control. Here's how you can stay in the loop!

This System Is Closed
This is a basic tutorial on closed-loop control systems. It covers the basic definitions and descriptions of how closed-loop systems work, a discussion of closed-loop summing points and how to use them, transfer functions, multi-loop closed-loop systems and closed-loop motor control. The direct link is www.electronics-tutorials.ws/systems/closed-loop-system.html.Electronics Tutorials www.electronics-tutorials.ws
PID Control
VeriCal in-situ calibration verification This is a basic discussion, with illustrations, of the principles of Proportional, Integral, Derivative (PID) and how it is used with controllers. It also covers tuning rules and starting settingf for common control loops. The direct link is at…

Through the looking glass of emerging technologies.

How might we expect emerging technologies to play out in the world of process control? Successfully predicting the future is difficult at best, so we sought out and consulted with industry visionaries and long-term planners to see where there is…

A Frost & Sullivan report, "Programmable Logic Controllers Market," finds that the market earned revenues of $10.37 billion in 2013 and estimates this will reach $14.58 billion in 2018.

According to analyst firm Frost & Sullivan, the global PLC market, which witnessed a strong decline in growth in 2012 due to the uncertain economic scenario in the developed world, has bounced back. Since 2013, it has witnessed positive growth, particularly in the Asia-Pacific region, where the rebound has been fueled by increased activity, especially in the construction, water and wastewater and power industries.
A Frost & Sullivan report, "Programmable Logic Controllers Market," finds that the market earned revenues of $10.37 billion in 2013 and estimates this will reach $14.58 billion in 2018.
In Europe, the need to enhance efficiency and comply with regulations, as well as improve safety and control capabilities, are driving…

Through the looking glass of emerging technologies.

How might we expect emerging technologies to play out in the world of process control? Successfully predicting the future is difficult at best, so we sought out and consulted with industry visionaries and long-term planners to see where there is…

Control Engineering Branches Out to Manage Critical Business Variables Such as Profitability, Risk, Asset Management and Cybersecurity

Most process engineers I talk to look back on the 1970s and 1980s as the heyday of control engineering, and in many ways it was. More engineers were focused on the applications of real-time control theory then than now. And when you look at how far…

The Latest in Computing Technology Is Here

VERSATILE AUTOMATION COMPUTERS These four new computers are designed for the challenging requirements of the machine automation industries. UNO-3073 and UNO-3073GL have Intel Celeron 1.1- MHz and 1.0-MHz processors; UNO-3083G and UNO-3085G have Intel Core i7 2.2- MHz processors. They have up to five PCI/PCIe expansion slots and support high-speed PCIe x16, x8, x4 and x1 cards and legacy PCI cards. Advantech Industrial Automation Group 800-205-7940www.advantech.com/ea
GAME-CHANGING PACs PACSystems RXi, a new control and computing platform, is designed for the needs of the industrial Internet. The core of the product family is a COM Express architecture with multi-core CPUs. Its configurations are unique in the industry, and able to…

Smart Drives, Mechatronics, Variable-Speed Drives and More Power Options

MEDIUM-VOLTAGE AC DRIVE MV1000 medium-voltage ac drives combine compact modular design, high efficiency and a good MTBF rate. Smart Harmonics technology reduces input total harmonic distortion to less than 2.5% without filters, which exceeds the requirements of IEEE519-1992. It also provides galvanic isolation between power input and output, and uses two 5-V step bridges per phase to generate a 17-level, line-to-line voltage output delivered to the motor. Yaskawa800-927-5292
VSD WITH SMARTSAltivar Process is a range of VSDs from 1 hp to 1,500 hp that come with embedded process knowledge, configurable on-board dashboards and a graphical HMI display. An advanced, secure, integrated web server lets operators access technical…

Since the goal is to control loop stability, the choice that gives you the best chance of that is the one to make.

Question:
Is there some general rule on when we should use =% (equal percentage) and when linear control valves? I know that the determining factor is the inherent flow characteristic, the flow vs. lift at constant pressure drop, or something like…

After six decades of developing on/off valve automation solutions, it might seem logical for Emerson Process Management to pause and take a well-deserved breather. But anyone who thinks that doesn't know how this company works. Just like the…

Smart Drives, Mechatronics, Variable-Speed Drives and More Power Options

MEDIUM-VOLTAGE AC DRIVE MV1000 medium-voltage ac drives combine compact modular design, high efficiency and a good MTBF rate. Smart Harmonics technology reduces input total harmonic distortion to less than 2.5% without filters, which exceeds the requirements of IEEE519-1992. It also provides galvanic isolation between power input and output, and uses two 5-V step bridges per phase to generate a 17-level, line-to-line voltage output delivered to the motor. Yaskawa800-927-5292
VSD WITH SMARTSAltivar Process is a range of VSDs from 1 hp to 1,500 hp that come with embedded process knowledge, configurable on-board dashboards and a graphical HMI display. An advanced, secure, integrated web server lets operators access technical…

Through the looking glass of emerging technologies.

How might we expect emerging technologies to play out in the world of process control? Successfully predicting the future is difficult at best, so we sought out and consulted with industry visionaries and long-term planners to see where there is…

Through the looking glass of emerging technologies.

How might we expect emerging technologies to play out in the world of process control? Successfully predicting the future is difficult at best, so we sought out and consulted with industry visionaries and long-term planners to see where there is…

Local automation pros can learn about key industry developments, gain development hours and upgrade their outdoor skills

Automation professionals in the Los Angeles area will be able to update their professional knowledge, explore key automation trends, receive professional development hours, meet leading industry experts—and improve their outdoor skills—when Siemens brings its Process Automation Tour to Bass Pro Shops in Rancho Cucamonga, Calif., on March 26, 2015.
Session topics will include:
Industrial security for process automation, including a review of the standards (IEC 62443), organizations (NIST) and proper implementations of those standards
Alarm management, with a focus on meeting ISA-18.2, condition monitoring of critical assets and improving operator effectiveness
Process safety management update, including how to keep your system compliant…

The GX and GP Products Are the First of a New SmartDAC+ Product Family

Yokogawa has released the GX and GP Series of digital data acquisition systems, products that go far beyond functionality of the original paperless recorder. Complementing Yokogawa's DXA Advanced R4 series, the GX and GP bring some features that are…

Recent

Because Big Data is Really More of the Same Data, Engineers and Other End Users Find Ways to Take Advantage of New Sources of Intelligence

I'm sorry to be a downer at the start of a shiny New Year, but I'm continually reminded that most new and unfamiliar technical concepts are just more of the same old concepts. Big data is really more of the same data. The Internet of Things (IoT)…

Reader says "NERC CIP does not make the grid more secure or reliable."

In response to Joe Weiss' blog post of Jan. 19, I totally disagree about NERC CIP not making the grid more secure or reliable. Just a few reasons. I have seen where control systems were operated without malware and ultimately became infected. At…

Diagnosing a signaled instrument failure is tricky, time-consuming and usually is called for at a most inconvenient time, but better diagnostics are making the task easier.

Physical Layer Diagnostic Improvements
Why is it, after weeks of seemingly trouble-free plant operation, the phone rings on the holiday weekend when the goose is in the oven and the table is set for dinner? Fortunately for me, the crew on shift was…

A badly designed network is often the weakest link in the system.

IoT's Weakest Link
A common conversation among many industrial networking specialists these days revolves around whether we should be distinguishing between wired and wireless networks. WINA, of which I am chairman, is one organization taking a…

We are destined to have a multiplicity of protocols in our facilities.

Regarding, John Rezabek's February On the Bus column: I think we are destined to have a multiplicity of protocols in our facilities. Actuators and sensors will be at the level of the not-Internet of Things; Ethernet makes no sense there. But…

This white paper is the first in a series to outline a new epoch of industrial automation. All aspects of control system reliability, security and lifecycle cost have been rethought from first principles.

Open Secure Automation™ from Bedrock delivers new levels of ICS reliability, embedded security and unified automation performance at much lower life cycle costs. The mission starts with reinventing the backplane. Bedrock's Backplane Module Interconnect (BMI) is designed with an advanced architecture, industrial grade materials and passive fail-safe principles. With a new foundation, automation can be rebuilt. There is no other way.
This white paper is the first in a series to outline a new epoch of industrial automation. All aspects of control system reliability, security and lifecycle cost have been rethought from first principles.
Download the white paper titled "Revolution" and learn more.

Mobility's True Value Lies in Enabling New Possibilities

Rockwell Automation takes seriously the needs of its users to access information when on the go. For years now, they've offered the ability to send text or email notifications to mobile devices or replicate in-plant or desktop user interfaces on…

Reader says "NERC CIP does not make the grid more secure or reliable."

In response to Joe Weiss' blog post of Jan. 19, I totally disagree about NERC CIP not making the grid more secure or reliable. Just a few reasons. I have seen where control systems were operated without malware and ultimately became infected. At…

As project details take shape, look to collaborative platforms and decoupled hardware and software development paths to speed execution efforts

As early project visioning shifts into more detailed engineering, it's time to take a much closer look at how the latest automation technology and project execution methodologies can be brought to bear for project success. Key automation…

Local automation pros can learn about key industry developments, gain development hours and upgrade their outdoor skills

Automation professionals in the Los Angeles area will be able to update their professional knowledge, explore key automation trends, receive professional development hours, meet leading industry experts—and improve their outdoor skills—when Siemens brings its Process Automation Tour to Bass Pro Shops in Rancho Cucamonga, Calif., on March 26, 2015.
Session topics will include:
Industrial security for process automation, including a review of the standards (IEC 62443), organizations (NIST) and proper implementations of those standards
Alarm management, with a focus on meeting ISA-18.2, condition monitoring of critical assets and improving operator effectiveness
Process safety management update, including how to keep your system compliant…

Coca-Cola and GE Lighting Use Proficy Workflow, Historian, iFix HMI SCADA and Portal Software to Streamline Lighting and Refreshment Production

Seeing is believing, and bringing operational information into the light makes it usable by everyone in an enterprise—allowing them all to make faster, more productive decisions.
This enhanced awareness was especially useful at GE Lighting,…

As project details take shape, look to collaborative platforms and decoupled hardware and software development paths to speed execution efforts

As early project visioning shifts into more detailed engineering, it's time to take a much closer look at how the latest automation technology and project execution methodologies can be brought to bear for project success. Key automation…

Find out what certification ABB Canada received and what B&B ELectronics' new name is.

ABB's operations in Canada have been certified by TÜV SÜD as having in place and applying a functional safety management system (FSMS) for the design and engineering of safety instrumented system (SIS) projects in accordance with industry good practice safety standards. These standards include IEC 61508 and IEC 61511 for the integration and implementation of safety instrumented systems. Networking technology provider B&B Electronics has changed its name to B+B SmartWorx. While continuing to develop mission-critical network connectivity technology for remote or demanding environments, B+B SmartWorx is expanding into the emerging Internet of Things market and embedding intelligence throughout the network connectivity stack from edge…

The Department of Homeland Security wants to help you prevent, respond to and recover from cyber attacks.

As we go to press, the U.S. Congress is threatening to suspend funding for the Department of Homeland Security (DHS). Some members are even calling for its dissolution. But assuming it's still around when you read this, you might consider enlisting…

What do 9/11, the Detroit Bomber and ICS Security Have in Common?

By Walt Boyes, Editor in Chief
In his "Unfettered" blog post, "What do 9/11, the Detroit Bomber and ICS Security Have in Common," Joe Weiss makes a really good point: The result of all governments' responses to the Dec. 25 incident on the approach…

Recent

Will Electronic Marshalling Mean the End of the "Bespoke" Enclosure?

Unlike clothing fashions, enclosure styles don't change a lot from year to year. A 40-year-old enclosure doesn't stand out like your dad's leisure suit. After all, a big metal box is pretty much a big metal box, even with the added glitz of…

Greg: Do you remember going into a control room and noticing right away something was wrong—such as the uneaten doughnuts or the food burning in the kitchen?

Stan: You knew it was bad if the operators were too busy to enjoy the finer things of control room life.

Greg: Oh, the memories of loops gone bad and processes gone wild! Fortunately, we’re getting good at forgetting. What were we talking about? Oh, yeah, how to deal with a gyrating plant. The first step is to tune the loops, but without the loop monitoring and learning tools, you have to wait until things calm down to do some step testing if the operator is fighting just to keep the plant running or the batch going.

Stan: You can check for bizarre tuning settings without interfering with the operator. The reset time setting is often too small on columns, stills, reactors, crystallizers and surge tanks. These unit operations are integrating processes or behave like integrating processes. Because of a process time constant so much larger than the loop dead time, the process response looks like a ramp in the time frame of interest. You can frequently get these loops to settle down by simply increasing the reset time by a factor of 10. If there were a bunch of oscillating loops, the root cause is often the loop furthest upstream. By far the most frequent bad actor is a level loop on a surge tank. Here the reset time is typically 100 times too small, causing slow rolling oscillations that ripple through the plant. Really bad news is a disturbance upstream with a period of oscillation close to the period of a loop, because the result is resonance where the oscillations get in phase and amplified by the loop.

Greg: Another common source of oscillations is a valve with excessive stick-slip (resolution limit) and backlash (dead band). It’s a valve instead of a tuning problem if the oscillations have a constant amplitude and period for a given reset and gain setting. Such limit cycles are mostly caused by valves, provided the controller is not banging between its output limits or the flat portions of a titration curve. Stick-slip causes loops with reset action to oscillate regardless of tuning settings. For stick-slip, the amplitude of the oscillations is relatively constant, but the period increases as the reset time increases and the controller gain decreases. Dead band causes a similar problem for a loop with double integration (integral time setting for an integrating process or integral time settings in both controllers of a cascade loop). For dead band, the amplitude in the process variable oscillation is inversely proportional to the controller gain. The period of a dead band oscillation is proportional to the reset time, like stick-slip, but the inverse relationship to controller gain is weaker.

Stan: A particularly confusing situation is when the reset action of a primary loop is faster than the reset action of a secondary loop, or when the reset action of any loop is faster than the slewing rate of a control valve or the velocity limit of a variable-speed drive. The loop looks fine for normal operation, but goes unstable for large load upsets or big set-point changes. The dynamic reset limiting option available today in a DCS can prevent the problem of the controller output outrunning its manipulated variable.

Greg: If a periodic disturbance is faster than the loop, the best a feedback controller can do is nothing. By the time it does something, it’s too late or puts the loop at risk for resonance. Really fast disturbances are better known as noise. Signal filters can make a measurement appear to be smoother and reduce the reaction of the loop, but the correct solution is to get rid of the disturbance. If this isn’t possible, the next best thing is to slow down or attenuate the disturbance and speed up the loop by getting rid of loop dead time and using a higher controller gain setting. The biggest source of dead time is often the time it takes for the controller to work its way through stick-slip or dead band. A high controller gain reduces this dead time.

Stan: Tuning and valve problems start out as flow disturbances, but can become concentration, pressure or temperature disturbances as they work their way through the process. Batch operations, start-ups, shutdowns, operator actions, interlocks, discrete process actions and level switches can cause big, abrupt and disruptive changes in flows.

Greg: The best way to slow down and reduce the amplitude of a concentration disturbance is to take advantage of a back-mixed volume between the disturbance and the loop. The mixing can be caused by turbulence from agitation, boiling or recirculation. The attenuation (reduction in amplitude) is proportional to the period of the concentration disturbance divided by the residence time of the volume (liquid inventory divided by total feed flow).

Stan: The largest unknown source of concentration disturbances is the raw materials. The culprit could be a change in the concentration of a key reactant or a contaminant that degrades process operation. Unfortunately, the composition of these raw materials may not even be measured in the lab. Furthermore, feed tanks usually don’t have agitators, so the only smoothing from the unloading of tank cars is from flow-entry turbulence and the slow migration of components from areas of high-to-low concentration.

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